Hey Ryuta,<br><br>Yes, we&#39;d thought about PIR&#39;s.  My understanding, and I&#39;d be happy to be proved wrong, is that they are either &#39;on&#39; or &#39;off&#39;, motion or no-motion.  <br><br>And this case what we&#39;d really like is to be able to detect motion but also depth (3d) so we can measure whether something is moving towards and away from the chimes with a proportional representation of force.  Then ideally lateral movement too so, say, someone waves their arm from side to side that that could also be measured.<br>
<br>Tricky &amp; challenging on such a lightweight machine, particularly with no GEM, but I guess that&#39;s also part of the fun:)<br><br>Many thanks for your suggestion though.<br><br>All the best,<br><br>Julian<br><br>
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